Image projection system engine assembly

ABSTRACT

A light projection engine uses a wide angle reflecting polarizer material (preferably 3M DBEF brand double brightness enhancement filter) as a polarizing beamsplitter to direct polarized light to beam splitter/combiner (such as an X-cube dichroic reflector). The beam splitter/combiner then splits the directed polarized light into separate reflective LCD panels acting as light valves. The LCD panels alter the polarity of the incident light from 0 degrees up to 90 degrees to control which light is passes from the wide angle reflecting polarizer back towards the light source and which light has the necessary polarization change to allow it to pass from the wide angle reflecting polarizer to the lens system. After reflecting off of the LCD panels, the light goes back through the X-cube dichroic reflector, where it is recombined. The recombined light which is of a first polarity is transmitted from the reflecting polarizer to the lens system, while the recombined light which is of a second polarity is transmitted to the light source. The LCDs are preferably analog polarizing LCDs.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to image projection engines. Moreparticularly, the present invention relates to an image projectionengine that provides a polarized image for use in, for instance, a“folded” projection system.

[0003] 2. Description of the Related Art

[0004] High power lamps are used for illumination applications beyondtypical incandescent and fluorescent lamps. One type of lamp known as ahigh intensity discharge (HID) lamp consists of a glass envelope whichcontains electrodes and a fill which vaporizes and becomes a plasma whenthe lamp is operated.

[0005] Recently, a patent issued for a high power lamp that utilizes alamp fill containing sulfur or selenium or compounds of thesesubstances. U.S. Pat. No. 5,404,076, issued to Dolan et al. and entitled“Lamp Including Sulfur” discloses an electrodeless lamp utilizing a fillat a pressure at least as high as one atmosphere. The fill is excited ata power density in excess of 50 watts per square centimeter. A lamputilizing the fill is excited at a power density of at least 60 wattsper square centimeter. The Dolan et al. patent is incorporated herein byreference Other pressures and power densities can be employed.

[0006] Projecting systems are used to display images on large surfaces,such as movie or television screens and computer displays. For example,in a front projection system, an image beam is projected from an imagesource onto the front side of a reflection-type angle transformingscreen, which then reflects the light toward a viewer positioned infront of the screen. In a rear projection system, the image beam isprojected onto the rear side of a transmission-type angle transformingscreen and transmitted toward a viewer located in front of the screen.

[0007] Projection engine designs are not new. For example, in U.S. Pat.No. 5,453,859 (hereby incorporated by reference), a system is shown thatuses a polarization beam splitter along with a dichroic “X-cube” tocreate a color image. Referring to FIG. 14 of that patent, it is seenthat polarized light from a light source 91 is reflected by apolarization beam splitter to a dichroic prism 95. The reflected lightis S-polarized, or polarized normal to the plane of incidence within theprism 93. This S-polarized light is then passed through a quarter waveplate 94, which circularly polarizes that S-polarized light. For eachpixel that is in the “off” position, that circularly polarized light isreflected unchanged by the corresponding pixel of a reflective LCD 96,97, and 98. Then, that circularly polarized light is restored to itsoriginal S-polarized state on the return path through the quarter waveplate 94. That light is then reflected back towards the light source bythe prism 93.

[0008] For pixels that are to be lit, the LCDs 96, 97, and 98 convertsome of the circularly polarized light to elliptically polarized light.When this light is passed through the quarter wave plate 94, the lightpassed will not be solely S-polarized, but will instead include aP-polarized component, which is passed through the prism 93, through aprojection lens 99, and into whatever projection system is used.

[0009] Displaytech, Inc., in a 6-page technical disclosure entitled“FLC/VLSI Display Technology” and dated Dec. 1, 1995; Parfenov et al.,in “Advanced optical schemes with liquid crystal image converters fordisplay applications,” SPIE Proceedings, Volume 2650, pages 173-179(Jan. 29-31, 1996); and Baur et al., in “High performance liquid crystaldevice suitable for projection display,” SPIE Proceedings, Volume 2650,pages 226-228 (Jan. 29-31, 1996), disclose background information on theuse of liquid crystal devices to process video images. These papers arehereby incorporated by reference.

SUMMARY OF THE INVENTION

[0010] The present invention provides an improved projection engine.Polarized light from a light source is reflected by a polarizer/analyzer(such as a 3M DBEF material) which reflects only the S-polarizedcomponents of light and transmits P-polarized components of light.

[0011] One of the polarized components of light is passed to an imageengine that forms an image by shifting the polarity of portions of thelight. For example, the S-polarized light can be passed to a dichroicX-cube beam splitter/combiner (or other beam splitter/combiner forsplitting the S-polarized light into red, green, and blue componentswhen light passes through the beam splitter/combiner in a firstdirection and for combining red, green, and blue components when lightpasses through the beam splitter/combiner in a second direction) whichprovides red, green, and blue light to spatial light modulator typeliquid crystal displays. Alternatively, the beam splitter/combiner couldbe omitted and a color sequential technique could instead be used toprovide colored light. In addition, a combination of the two techniquescan be employed. The liquid crystal displays alter the polarity of theS-polarized light so that the reflected light is S-polarized,P-polarized, or elliptically polarized with both S-polarized andP-polarized components, depending on the amount of light that is to betransmitted to the display and the type of spatial light modulator. Thislight, if the polarity is unchanged, is reflected back to the lightsource by the polarizer/analyzer. Any P-polarized components, however,are passed through the polarizer/analyzer and on to the display.

[0012] Using this system, a variable intensity of each color can beapplied with each pixel, and each resulting pixel is generated throughthe coaligned colors of light. Further, the optics are highly efficient,because virtually all of the source light of an “on” pixel istransmitted for display and virtually all of the source light of an“off” pixel is returned to the lamp where its energy may be recovered.

[0013] The beam splitter/combiner is chosen such that there is either noalteration of the polarity of light passing therethrough (the preferredsituation) or a consistent, predictable alteration of the polarity sothat compensation for the alteration of polarity can be made bycontrolling the LCDs. For example, if a beam splitter/combiner that ischosen for use alters the polarity of green light passing back and forththrough it one quarter wave total, the LCDs for the green light would beadjusted such that if one wanted a dark pixel, one would cause the LCDto alter the polarity back one quarter wave in the opposite direction toend up with a green light beam that is reflected back at the source fromthe DBEF reflective surface.

[0014] The present invention preferably comprises a projection displayapparatus comprising:

[0015] a source of rays of polarized light;

[0016] a 3M DBEF reflecting polarizer aligned at an angle to the rays ofpolarized light for passing substantially all of the rays of polarizedlight which are polarized in a first direction and for reflectingsubstantially all of the rays of polarized light which are polarized ina second direction;

[0017] a beam splitter/combiner, having a first, primary incidence planealigned with the reflected polarized light for splitting the rays ofpolarized light which are polarized in the second direction into blue,green, and red light rays;

[0018] a first reflecting polarizing LCD for receiving the blue lightrays from the beam splitter/combiner, shifting the polarization of none,some, or all of the blue light rays, and directing the blue light raysback into the beam splitter/combiner;

[0019] a second reflecting polarizing LCD for receiving the green lightrays from the beam splitter/combiner, shifting the polarization of none,some, or all of the green light rays, and directing the green light raysback into the beam splitter/combiner;

[0020] a third reflecting polarizing LCD for receiving the red lightrays from the beam splitter/combiner, shifing the polarization of none,some, or all of the red light rays, and directing the red light raysback into the beam splitter/combiner; and

[0021] a lens for receiving and transmitting substantially all of therays of polarized light which are polarized in the first direction andwhich have passed from the beam splitter/combiner through the DBEFreflecting polarizer.

[0022] Preferably, the source of rays of polarized light comprises a“light-pumped” source that can re-absorb and re-emit unused reflectedlight; when a “light-pumped” source is used, the apparatus can alsoinclude a mirror aligned at substantially a 90° angle to the rays ofpolarized light as the rays exit the source for reflecting back to thesource the rays of polarized light which are polarized in a firstdirection and which pass through the DBEF reflecting polarizer withoutfirst passing through the beam splitter/combiner. The source of rays ofpolarized light preferably includes a reflecting polarizing filter forpassing substantially all of the rays of polarized light which arepolarized in the second direction and for reflecting substantially allof the other rays of light. The source of rays of polarized lightpreferably also comprises a reflecting filter for passing substantiallyall rays of blue light, green light, and red light, and for reflectingsubstantially all rays of light which are not blue light, green light,or red light.

[0023] A condenser lens can advantageously be interposed along the pathof the rays of polarized light between the source of rays of polarizedlight and the DBEF polarizing reflector.

[0024] The source of rays of polarized light can advantageouslycomprise:

[0025] an electrodeless lamp body that defines a chamber;

[0026] a gas contained within the chamber;

[0027] electrodes positioned externally of the lamp chamber forproducing radio frequency energy that excites the gas, forming a plasmalight source of intense heat that emits a light beam, wherein theelectrodes are not subjected to the intense heat generated at theplasma; and

[0028] a reflector positioned next to the lamp body for redirecting someof the light emitted by the light source back to the lamp using thereflector so that the lamp reabsorbs light energy to intensify the lightsource, wherein the reflector includes a polarizing filter that ispositioned to receive and polarize the light beam.

[0029] The projection display apparatus of the present invention canadvantageously be used as an image source in a projection apparatus forproducing an image display on a display surface comprising a displaysurface, an optical device which is reflective of some light andtransmissive of other light; and means for transmitting light from theimage source to the display surface such that the light travels an imagepath which reaches the optical device twice on its way to the displaysurface.

[0030] The present invention also comprises a method of producing avisual image comprising:

[0031] providing a source of rays of polarized light;

[0032] directing the rays of polarized light onto a 3M DBEF reflectingpolarizer aligned at an angle to the rays of polarized light for passingsubstantially all of the rays of polarized light which are polarized ina first direction and for reflecting substantially all of the rays ofpolarized light which are polarized in a second direction;

[0033] reflecting the light rays which are aligned in the seconddirection from the 3M DBEF reflecting polarizer into a beamsplitter/combiner having a first, primary incidence plane aligned at anangle to the 3M DBEF reflecting polarizer for splitting the rays ofpolarized light which are polarized in the second direction into blue,green, and red light rays;

[0034] valving the blue light rays in a first reflecting polarizing LCDfor receiving the blue light rays from the beam splitter/combiner, byshifting the polarization of none, some, or all of the blue light rays90°, and directing the blue light rays back into the beamsplitter/combiner;

[0035] valving the green light rays in a second reflecting polarizingLCD for receiving the green light rays from the beam splitter/combiner,by shifting the polarization of none, some, or all of the green lightrays 90°, and directing the green light rays back into the beamsplitter/combiner;

[0036] valving the red light rays in a third reflecting polarizing LCDfor receiving the red light rays from the beam splitter/combiner, byshifting the polarization of none, some, or all of the red light rays90°, and directing the red light rays back into the beamsplitter/combiner;

[0037] electrically controlling the LCDs;

[0038] reflecting the blue, green, and red light rays polarized in thesecond direction from the 3M DBEF reflecting polarizer back to thesource of rays of polarized light; and

[0039] transmitting the blue, green, and red light rays polarized in thefirst direction through the 3M DBEF reflecting polarizer to a lens whichtransmits the blue, green, and red light rays polarized in the firstdirection to produce a visual image. In this method, the source of raysof polarized light preferably comprises a “light-pumped” source that canre-absorb and re-emit unused reflected light. The method preferablyfurther comprises the step of reflecting back to the source of rays ofpolarized light the rays of polarized light which are polarized in afirst direction and which pass through the DBEF reflecting polarizerwithout first passing through the beam splitter/combiner from a mirroraligned at substantially a 90° angle to the rays of polarized light asthe rays exit the source.

[0040] The source of rays of polarized light preferably includes asource of light and a reflecting polarizing filter for passingsubstantially all of the rays of polarized light which are polarized inthe second direction and for reflecting substantially all of the otherrays of light.

[0041] The source of rays of polarized light can also include reflectingfilter for passing substantially all rays of blue light, green light,and red light, and for reflecting substantially all rays of light whichare not blue light, green light, or red light.

[0042] In the method of the present invention, the LCDs are preferablyanalog LCDs.

[0043] The apparatus of the present invention can be broadly describedas a projection display apparatus comprising:

[0044] an optically pumpable source of rays of polarized light that canre-emit unused light returned to it;

[0045] a wide angle reflecting polarizer for passing substantially allof the rays of polarized light which are polarized in a first directionand for reflecting substantially all of the rays of polarized lightwhich are polarized in a second direction;

[0046] at least one reflecting polarizing LCD for receiving the lightrays from the reflecting polarizer, shifting the polarization of none,some, or all of the light rays, and directing the light rays backtowards the wide angle reflecting polarizer;

[0047] a lens for receiving and transmitting substantially all of therays of polarized light whose polarization has been shifted by the atleast one reflecting polarizing LCD; and

[0048] means for returning the rays of polarized light whosepolarization has not been shifted by the at least one reflectingpolarizing LCD to the source of rays of polarized light to opticallypump the source.

[0049] The method of the present invention can broadly be described as amethod of producing a visual image comprising:

[0050] providing an optically pumpable source of rays of polarized lightthat can re-emit unused light returned to it;

[0051] directing the rays of polarized light onto a wide anglereflecting polarizer for passing substantially all of the rays ofpolarized light which are polarized in a first direction and forreflecting substantially all of the rays of polarized light which arepolarized in a second direction;

[0052] using at least one reflecting polarizing LCD, shifting thepolarization of none, some, or all of the light rays, and directing thelight rays back towards the wide angle reflecting polarizer;

[0053] receiving with a lens and transmitting through the lenssubstantially all of the rays of polarized light whose polarization hasbeen shifted by the at least one reflecting polarizing LCD; and

[0054] returning the rays of polarized light whose polarization has notbeen shifted by the at least one reflecting polarizing LCD to the sourceof rays of polarized light to optically pump the source.

BRIEF DESCRIPTION OF THE DRAWINGS

[0055] For a further understanding of the nature and objects of thepresent invention, reference should be had to the following detaileddescription, taken in conjunction with the accompanying drawings, inwhich like parts are given like reference numerals, and wherein:

[0056]FIG. 1 is a sectional view of the preferred embodiment of theapparatus of the present invention;

[0057]FIG. 1A is a fragmentary view of the preferred embodiment of FIG.1;

[0058]FIG. 2 is a sectional elevational view of a second embodiment ofthe apparatus of the present invention;

[0059]FIG. 3 is a sectional elevational view of a third embodiment ofthe apparatus of the present invention;

[0060]FIG. 4 is a sectional elevational view of a fourth embodiment ofthe apparatus of the present invention;

[0061]FIG. 5 is a sectional elevational view of a fifth embodiment ofthe apparatus of the present invention;

[0062]FIG. 6 is a sectional view of the sixth embodiment of theapparatus of the present invention;

[0063]FIG. 7 is a sectional view of the seventh embodiment of theapparatus of the present invention;

[0064]FIG. 8 is a sectional view of the eighth embodiment of theapparatus of the present invention;

[0065]FIGS. 9 and 10 are side views of the preferred embodiment of theapparatus of the present invention showing a rear projection videosystem;

[0066]FIG. 11 is a perspective view of the projection display apparatusof an embodiment of the present invention;

[0067]FIG. 12 is a top view of the projection display apparatus of anembodiment of the present invention;

[0068]FIG. 12A is a top view of the projection display apparatus of analternative embodiment of the present invention;

[0069]FIG. 13 is a top view of the projection display apparatus of anembodiment of the present invention;

[0070]FIG. 14 is a top view of the projection display apparatus of analternative embodiment of the present invention;

[0071]FIG. 14A is a top view of an embodiment of the present inventionthat uses sequential color;

[0072]FIG. 15 is a top view of the projection display apparatus ofanother embodiment of the present invention;

[0073]FIG. 16 is a top view of the projection display apparatus ofanother alternative embodiment of the present invention; and

[0074]FIG. 17 is a top view of the projection display apparatus of yetanother alternative embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0075] U.S. application Ser. No. 08/581,108, filed Dec. 29, 1995, andentitled “Projecting Images,” is hereby incorporated by reference.

[0076] Turning to the drawings, FIG. 1 shows generally an embodiment ofthe lamp apparatus of the present invention, designated generally by thenumeral 10A, for use with the projector lamp optics assembly of thepreferred embodiment of the present invention. A high efficiency lampapparatus 10A includes a bulb 11 having a hollow interior 12 thatcontains a gas such as sulfur gas or selenium gas or some other lampoptimally capable of being optically pumped. The gas in bulb 11 can beexcited to a plasma state so as to produce a high intensity lightsource. The gas fill is excited by electrodes E (see FIG. 1A), whichprovide radio frequency (or other appropriate frequency) energy toexcite the fill; electrodes E are not subjected to the intense heat ofthe plasma inside bulb 11. Lamp apparatus 10A could also include anon-mercury containing metal halide lamp which works with fusion and iselectrodeless. The fill may be high or low pressure.

[0077] Generally, redirecting light to a lamp will cause that lamp tofail. This is not true, however, with certain types of electrodelesslamps that can reabsorb such light. Such lamps include those shown inthe Dolan patent, previously incorporated by reference, as well ascertain lamps containing selenium gasses or non-mercury metal halidegasses. The advantage of using such lamps in the disclosed systems isthat generally only certain colors or polarities of light are useableand needed in these systems. Therefore, with appropriate filtering(illustrated by FIGS. 1-8), only desired polarities or colors of lightare passed, and the remainder is reflected back to the plasma formed inthe electrodeless lamps for re-absorption and re-emission. This improvesthe efficiency of the light source.

[0078] A shaped (for instance, parabolic) annular reflector housing 14is positioned about and spaced from bulb 11 as shown in FIG. 1. Thehousing 14 is hollow, defined by a wall 15 and an open end portion 16.The wall 15 has a reflecting surface 17. Housing 14 can be made of, forexample, ceramic material.

[0079] A first transversely positioned screen 18 is interposed acrossthe path of a light beam 19 that is travelling from the bulb 11 throughthe open end partition 16 in the direction of arrows 20. A second screen21 is interposed across the path 19 and on the opposite side of screen18 from bulb 11 as shown in FIG. 1.

[0080] The first screen 18 is preferably an interference filter (forexample a dichroic filter or dichroic mirror), that reflects certaincolors of light while allowing others to pass through. The screen 18 ispreferably selected to pass red, green and blue light, reflectingundesired colors back to the bulb 11 and the reflector surface 17. Byreflecting light other than desired colors back to the bulb 11, the lamp10 becomes more efficient because it allows conversion of redirectedlight back to useful wavelengths. In FIG. 1, the lamp 10A has the screen18 mounted inside the reflector housing 14 and the screen 21 mounted atopening 16. The screen 18 and the screen 21 each extends at itsperiphery to the wall 15.

[0081] The screen 21 is a reflecting polarizer that only allows acertain polarity of light to pass through as indicated by the arrows 20.The reflecting polarizer 21 reflects light of the wrong polarity back tothe bulb 11. Therefore, in the lamp 10A, emitted light indicated as 20has been filtered to be of a desired portion(s) of the color spectrumand of a desired polarity.

[0082] In FIGS. 2-8, other embodiments of the lamp 10 are shown. FIG. 2illustrates a lamp 10B similar to that of FIG. 1, with a pair of screens26 and 27 positioned externally or covering an opening 23 of a reflectorhousing 22. The screen 26 is preferably an interference filter, and thescreen 27 is preferably a reflecting polarizer. FIG. 3 illustrates analternative lamp 10C, in which three optical elements 31, 32, and 33 arepositioned external to a housing 28 and either away from or covering anopen end portion 29 of the housing 28. The element 31 is preferably areflecting polarizer, the element 32 is preferably an interferencefilter, and the element 33 is a clean-up absorbing filter. FIG. 4illustrates another alternative lamp 10F, with an element 108 that is aninterference filter and an element 110 that is a reflecting polarizerboth mounted within a reflector housing 100, while an additionalpolarizing filter 114 covers an open end 102 of the reflector housing100. FIG. 5 illustrates an alternative lamp 10G where a reflectivehousing 116 assumes a parabolic shape. FIG. 6 illustrates lamp 10D inwhich a reflector housing 35 has an inner reflecting surface 37 withdouble parabolic shapes and cross-sections. FIG. 7 illustrates analternative lamp 10E, in which an opening 44 has an element 45 that isan interference filter, dichroic filter, or dichroic mirror, and anelement 46, which is preferably a reflecting polarizer. FIG. 8illustrates an alternative lamp 10H with dual parabolic reflectors thatincludes an internal element 138 that is preferably an interferencefilter and an element 136 covering an opening 134, where the element 136is preferably a reflecting polarizer. All of these lamps 10 are intendedto provide desired frequencies and polarities of light, while reflectingundesired light for re-absorption and re-emission by the fill within thebulb 11.

[0083]FIGS. 9 and 10 show a rear projection video system 60 thatincludes a linear reflecting polarizer 62 and an achromatic retarder 64that allow light in a projected image 66 to reflect from a displayscreen 68 at one instance and to pass through the screen 68 at anotherinstance. This allows for “optical folding,” which allows the videosystem 60 to be very shallow yet project a large image, as described inthe previously incorporated U.S. patent application entitled “ProjectingImages.” For the video system 60 to work properly, the image source 76must produce polarized light. A wide variety of other types of videosystems employ polarization in image formation.

[0084]FIGS. 11 and 12 show the projection display apparatus or engine200 of a first embodiment of the present invention. The projectiondisplay apparatus 200 comprises a source 210 of rays of polarized light,such as the light source 10A of FIG. 1, a polarizer/analyzer (reflectingpolarizer) 220, an X-cube beam splitter/combiner 230, reflectingpolarizing LCDs 241, 242, 243, a mirror 250, a projection lens 260, anoptional clean-up polarizing filter 261, and an optional condenser lens270. The projection display apparatus 200 (or any of the remainingembodiments, which employ a wide angle reflecting polarizer) canadvantageously be used as the image source 76 in the video system 60shown in FIGS. 9 and 10.

[0085] The reflecting polarizer 220 (preferably made of DBEF, or doublebrightness enhancement film, commercially available from MinnesotaMining & Manufacturing Company, though some other wide angle reflectingpolarizer could be used) is preferably aligned at approximately a 45°angle to the rays of polarized light for passing substantially all ofthe components of light polarized in a first direction (P-polarized in adirection parallel to the plane of incidence) and for reflectingsubstantially all of the components of light polarized in a seconddirection (S-polarized, in a direction normal to the plane ofincidence). The reflecting polarizer 220 could be set to work at anglesother than 45°, with corresponding changes to the remainder of theoptics to account for the other angles. FIG. 12A shows an alternativeembodiment in which the angle of incidence of the light projected by thesource 210 to the reflecting polarizer 220 is other than 45°. When thereflecting polarizer is an appropriate wide angle reflecting polarizer,such as DBEF, angles other than 45° can be chosen.

[0086] The X-cube beam splitter/combiner 230 has a first, primaryincidence plane 231 aligned at approximately a 45° angle to thereflecting polarizer 220. The purpose of the X-cube beamsplitter/combiner 230 is to split the rays of S-polarized light intoblue, green, and red light rays and to direct substantially all of afirst light color (such as blue light rays) through a second plane ofthe X-cube beam splitter/combiner 230, to direct substantially all of asecond light color (such as green light rays) through a third plane ofthe X-cube beam splitter/combiner 230, and to direct substantially alljof a third light color (such as red light rays) through a fourth planeof the X-cube beam splitter/combiner 230. While red, green, and blue areshown in this embodiment, any three colors suitable as primary colorscould be used.

[0087] A first reflecting polarizing LCD 241 receives the blue lightrays from X-cube beam splitter/combiner 230. The reflecting polarizingLCD 241 (and the reflecting polarizing LCDs 242 and 243) is preferably aliquid crystal spatial light modulator. These LCDs operate as a type ofvariably birefringent switch. In a first position, the reflected lightis essentially unaffected by the LCD, resulting in the reflective lightbeing S-polarized as was the incident light. When the liquid crystalsare fully energized, however, the liquid crystal display effectivelyretards the incident light by a half wave, resulting in a rotation ofthe polarity by 90°. Thus, the S-polarized light is reflected asP-polarized light. In between, if appropriate for the particular LCD,components of each are apparent, resulting in elliptically polarized orcircularly polarized light, with a greater and lesser degree ofpolarization in a particular direction according to the amount ofvoltage applied to that particular pixel of the LCD of the reflectingpolarizing LCD 241. For alignment purposes, the optical axis of theliquid crystal display is aligned at a 45° angle relative to the angleof polarization of the incident S-polarized light.

[0088] Thus, the reflecting polarizing LCD 241 shifts the polarizationof the blue light rays such that the reflected light has varying degreesof S-polarized components and P-polarized components, varying fromentirely S-polarized to entirely P-polarized. These rays are directedback into the X-cube beam splitter/combiner 230.

[0089] The second reflecting polarizing LCD 242 is used for receivingthe green light rays from X-cube beam splitter/combiner 230, and likethe first reflecting polarizing LCD 241 shifts the polarization of theS-polarized light so that the result is no, some, or all P-polarizedlight. The green light rays are then directed back into the X-cube beamsplitter/combiner 230. The third reflecting polarizing LCD 243 does thesame for the red light rays from the X-cube beam splitter/combiner 230.

[0090] In operation, radio-frequency (such as microwave) energy is usedto excite the fill in light bulb 11, and light is emitted therefrom.Some of this light (the blue, green, and red components) passes throughreflecting filter 18. The rest of the light is reflected by reflectingfilter 18 back into light bulb 11.

[0091] Of the light which passes from the bulb 11 through the filter 18,substantially all of the transmitted light is S-polarized, while theremaining light is reflected back towards the bulb 11 from the filter21. A small amount of P-polarized light 222 may escape through filter21, but it will pass unreflected through reflecting polarizer 220,reflect off of a mirror 250, and back through a second surface 227 ofthe reflecting polarizer 220 towards the filter 21, through which itwill pass. The insulated filter 21 does not normally pass P-polarizedlight in a first direction when the light is coming from the bulb 11,but normally passes P-polarized light in a second direction when thelight is coming from outside of the light source 210. This initiallyP-polarized light is then directed to the bulb 11 for optical pumping.

[0092] It will be appreciated that the mirror 250 is not strictlynecessary. This is especially true if the source 210 initially provideslight of only the desired polarity. In that case, very little light willactually pass through the reflecting polarizer 220 anyway, so the mirror250 can be eliminated. Even if the light is not prefiltered in this way,the mirror 250 could be eliminated without detracting from the spirit ofthe invention.

[0093] The S-polarized light 221, after passing through the filter 18(and a condenser lens 270, if present) reflects off of a first surface226 of the reflector 220 and into the first, primary incidence plane 231of the X-cube beam splitter/combiner 230. The X-cube beamsplitter/combiner 230 then splits the rays of S-polarized light intoblue, green, and red light rays and directs substantially all blue lightrays through a second plane 232 of the X-cube beam splitter/combiner230, directs substantially all green light rays through a third plane233 of the X-cube beam splitter/combiner 230, and directs substantiallyall red light rays through a fourth plane 234 of the X-cube beamsplitter/combiner 230.

[0094] The light is then reflected by the LCDs 241, 242, and 243, asdescribed above. The LCDs 241, 242, 243 are electrically controlled,such as with television signals, signals from a personal computer, orother means discussed in co-pending U.S. patent application entitled“Projecting Images.” As discussed above, the reflected light is eithertotally S-polarized (unchanged), totally P-polarized, or ellipticallypolarized with components of each.

[0095] Both the P-polarized and S-polarized components of the light rays223 again pass through and out of the X-cube beam splitter/combiner 230.When the light strikes the reflecting polarizer 220, the P-polaritycomponents pass through, while the S-polarity components are reflected.The P-polarized components pass through the projection lens 260 andclean-up polarizing filter 261 (if present) and out of the apparatus200, providing an image source for, for example, the apparatus 60. Theremaining S-polarized components are reflected by the reflectingpolarizer 220 and directed back into the light source 210, serving to“optically pump” the bulb 11.

[0096] Thus, as one will appreciate from a description of FIGS. 11 and12, substantially all light emanating from bulb 11 is either transmittedthrough projecting lens 260 or is reflected back into bulb 11 for re-use(perhaps after sufficient down-shifting takes place).

[0097] The LCDs 241, 242, 243 currently can be analog LCDs in the sensethat the amount of polarization change for a pixel is related to thevoltage level applied to that pixel. This allows the intensity of eachcolor to be individually adjusted, providing for multiple colors.Alternatively, the LCDs 241, 242, 243 can be ferroelectric LCDs, whereeach pixel is instead only on or off, and then one pulse width modulateswithin each frame and/or performs frame-to-frame modulation toapproximate a desired brightness for a color.

[0098]FIG. 13 is a top view of the projection display apparatus 300 ofan embodiment of the present invention. The projection display apparatus300 is essentially the same as the apparatus 200, but X-cube beamsplitter/combiner 230 of the apparatus 200 is replaced with a Phillipsprism 330, and the reflecting polarizing LCDs 241, 242, 243 are replacedwith the reflecting polarizing LCDs 341, 342, 343, respectively. ThePhillips prism 330 includes a plane 334 through which red light istransmitted, a plane 333 through which green light is transmitted, and aplane 332 through which blue light is transmitted. The reflectingpolarizing LCDs 341, 342, 343 work in the same manner as the reflectingpolarizing LCDs 241, 242, 243.

[0099]FIG. 14 is a top view of the projection display apparatus 400 ofan alternative embodiment of the present invention. The projectiondisplay apparatus 400 is essentially the same as the apparatus 200, butX-cube beam splitter/combiner 230 of the apparatus 200 is replaced witha prism 430, the reflecting polarizing LCDs 241, 242, 243 are replacedwith the reflecting polarizing LCDs 441, 442, 443, respectively, and anumber of optional polarizing filters are included in the apparatus 400.

[0100] The optional polarizing filters shown in FIG. 14 include theclean-up polarizing filter 261, a pre-polarizer 264 immediatelydownstream of the lamp 210 to provide clean-up polarization, anabsorptive polarizer 263 laminated to the polarizer/analyzer 220, and/oran absorptive polarizer 262 between polarizer/analyzer 220 and lens 260for clean-up. Any or all of the filters 261, 262, 263, and 264 could beomitted, or all could be included, in apparatus 400; likewise, any orall of these filters could be included in the apparatus of otherembodiments of the present invention described herein.

[0101] The prism 430 includes a plane 434 through which red light istransmitted, a plane 433 through which green light is transmitted, and aplane 432 through which blue light is transmitted. The reflectingpolarizing LCDs 441, 442, 443 work in the same manner as the reflectingpolarizing LCDs 241, 242, 243.

[0102]FIG. 14A is a top view of the projection display apparatus 450 ofanother embodiment of the present invention. The projection displayapparatus 450 is similar to the apparatus 200 but only a singlereflecting/polarizing LCD 452 is used and no bean splitter/combine isutilized. A color wheel or shutter 451 is provided prior to thepolarizer/analyzer 220. The color wheel 451 acts to providetime-sequential red, green, and blue light, so that the projectiondisplay apparatus 450 is a color sequential system. Thereflecting/polarizing LCD 452 then receives red, green and blue dataduring the appropriate period in synchronization with the color wheel451. The viewer's eye then integrates the three separate images into asingle multicolor image.

[0103]FIG. 15 is a top view of the projection display apparatus 500 ofanother embodiment of the present invention. The projection displayapparatus 500 is similar to the apparatus 200, but X-cube beamsplitter/combiner 230 of the apparatus 200 is replaced with a prism 530,and the reflecting polarizing LCDs 241 and 243 are replaced with thereflecting polarizing LCDs 541 and 543, respectively. The reflectingpolarizing LCD 242 is omitted.

[0104] The prism 530 includes a plane 534 through which a single colorlight, for example, red, is transmitted and a plane 532 through whichtwo colors of light, blue and green for example, are transmitted. Thereflecting polarizing LCDs 541 and 543 work in the same manner as thereflecting polarizing LCDs 241 and 243. Reflecting polarizing LCD 541operates like reflective polarized LCD 452 of FIG. 14A, except thatsequential modulation is done of only two colors.

[0105]FIG. 16 is a top view of the projection display apparatus 600 ofanother alternative embodiment of the present invention. The projectiondisplay apparatus 600 is similar to the apparatus 500, but the prism 530of the apparatus 500 is replaced with a prism 630, and the reflectingpolarizing LCDs 541 and 543 are replaced with the reflecting polarizingLCDs 641 and 643, respectively.

[0106] The prism 630 includes a planar surface 634 through which a firstcolor of light is transmitted and a planar surface 632 through which twoother colors of light are transmitted. The reflecting polarizing LCDs641 and 643 work in the same manner as the reflecting polarizing LCDs541 and 543.

[0107]FIG. 17 is a top view of the projection display apparatus of yetanother alternative embodiment of the present invention, projectiondisplay apparatus 700. The projection display apparatus 700 is perhapsmost similar to the projection display apparatus 300, but works on areflective, rather than transmissive, principle. In apparatus 700, thelight source 210 is replaced with a light source 710, and the lightsource 710 primarily produces P-polarized light 222 and onlyincidentally produces S-polarized light 221. In the apparatus 700, thepositions of the light source 710 and the lens 260 are switched; mirror250 still reflects light of an undesired polarity back into the lightsource 710, but in this case the undesired polarity is S-polarizedlight. The reflecting polarizing LCDs 341, 342, 343 work in the samemanner as in the apparatus 300, changing the polarity of so much of thelight as is desired to be transmitted to lens 260.

[0108] Apparatus 200, 400, 450, 500, and 600 could all be modified toreflect from polarizer/analyzer 220 rather than transmit throughpolarizer/analyzer 220 an image into lens 260.

[0109] For monochrome applications, one could modify the projectiondisplay apparatus 200 to omit the beam splitter/combiner 230 and LCDs241 and 243. Alternatively, if one wished to use a reflective principlewith a monochrome application, one could use the apparatus 700 but omitthe prism 330 and the LCDs 341 and 343.

[0110] The projection display apparatus 200, 300, 400, 450, 500, 600,and 700 is advantageous over systems such as those shown in U.S. Pat.No. 5,453,859 in part because a wide angle reflecting polarizer (such as3M DBEF) is used as the reflecting polarizer 220. Further, the filters21 and 18 and the mirror 250, if used, cause a substantial portion ofthe light to be redirected into lamp 11 for absorption and re-emission.Additionally, any light reflected from an “off” pixel in the reflecting,polarizing LCDs is reflected back to the lamp 11 by the action of theLCD and the polarizer/analyzer 220 as the “off” pixel light has not beenretarded by the LCD, so the polarization is such that the light isreflected by the polarizer/analyzer 220 back to the lamp 11. Thus,efficiency is increased at a system level due to these types ofreflected light.

[0111] As used herein, “wide angle reflecting polarizer” means areflecting polarizer that substantially transmits light of onepolarization and reflects light of another through a wide variation inangles. Typical reflecting polarizers only operate properly at an anglevery close to the Brewster angle. Wide angle refection polarizersoperate at a variety of angles.

[0112] It will also be appreciated that a variety of other opticalcomponents can be included in the embodiments disclosed in FIGS. 11-17.For example, the light out of the source 210 could be immediatelypolarized, with the needed polarity of light reflected into the source.This could occur, for example, between the lens 270 and the source 210.Further, the lens 270 could be placed at different points in the opticalpath without detracting from the spirit of the invention. Also, althougha variety of devices are shown for creating the polarized image, thespecific device is not critical. A wide variety of image engines whichcreate a polarized image could be used with the wide angle reflectingpolarizer in a system according to the invention. For example, insteadof providing three LCDs 241, 242, and 243 as shown in FIG. 12, a colorsequential system using a single LCD could be used. By using a wideangle reflecting polarizer in a system that utilizes polarization tocreate images, the tolerances are relaxed and the system becomes easierto construct and maintain.

[0113] The foregoing embodiments are presented by way of example only;the scope of the present invention is to be limited only by thefollowing claims.

What is claimed is:
 1. A projection display apparatus comprising: alight source providing a beam of light; a wide angle reflectingpolarizer for passing substantially all of a first polarized portion ofthe beam that is polarized in a first direction, and reflectingsubstantially all of a second polarized portion of the beam that ispolarized in a second direction; and an image engine that receives oneof the first or second polarized portions and returns to said wide anglereflecting polarizer a polarized image in which the polarization of theone of the first or second polarized portions is shifted correspondingto an image to display to include components of the second or firstpolarized portion.
 2. The apparatus of claim 1, wherein the wide anglereflecting polarizer comprises 3M DBEF.
 3. The apparatus of claim 1,wherein the image engine further includes a beam splitter/combiner forsplitting rays of polarized light received from the reflecting polarizerinto plural color bands, wherein there is a reflecting polarizing LCDfor each color band and an individual planar surface of the beamsplitter/combiner for each color band, and each color band is directedsubstantially through its respective individual planar surface of thesplitter/combiner to its respective reflecting polarizing LCD, andthence through its respective planar surface into the beamsplitter/combiner, where the plural color bands are combined andtransmitted to the wide angle reflecting polarizer.
 4. The apparatus ofclaim 3, wherein the LCD is an analog LCD.
 5. The apparatus of claim 1,wherein the image engine further includes a beam splitter/combiner forsplitting rays of polarized light received from the reflecting polarizerinto a first and second color band, wherein the first color band ispassed through a color wheel/shutter to a single LCD for colorsequential operation, and wherein the second color band is passed to asecond LCD.
 6. The apparatus of claim 1, further comprising a mirror forreflecting back to the light source light which is not transmitted tothe image engine, wherein the light source reabsorbs and reemits atleast a portion of the light which is not transmitted to the imageengine.
 7. The apparatus of claim 1, wherein the light source comprisesa lamp and a reflecting polarizing filter for passing substantially allof the rays of polarized light which are polarized in the seconddirection and for reflecting substantially all of the other rays oflight back into the lamp for energy recovery.
 8. The apparatus of claim1, wherein the light source comprises a lamp and a reflecting filter forpassing substantially all rays of selected wavelength bands and forreflecting substantially all rays of light which are not in these bandsback into the lamp for energy recovery.
 9. The apparatus of claim 1,further comprising a means of modifying the direction of the rays oflight.
 10. The apparatus of claim 1, wherein the light source comprises:i) an electrodeless lamp body that defines a chamber; ii) a gascontained within the chamber; iii) electrodes positioned externally ofthe lamp chamber for producing energy that excites the gas, forming aplasma light source of intense heat that emits a light beam; iv) whereinthe electrodes are not subjected to the intense heat generated at theplasma; v) a reflector positioned next to the lamp body for redirectingsome of the light emitted by the light source back to the lamp using thereflector so that the lamp reabsorbs light energy to intensify the lightsource; and vi) wherein the reflector includes a polarizing filter thatis positioned to receive and polarize the light beam.
 11. The apparatusof claim 1, further comprising: a projection apparatus for producing animage display on a display surface, the projection apparatus including:i) a display surface; ii) an optical device; and iii) means fortransmitting light from the lens to the display surface such that thelight travels an image path which reaches the optical device twice onits way to the display surface, wherein the optical device is reflectiveof some light and transmissive of other light.
 12. The apparatus ofclaim 1, wherein the image engine receives the first polarized portionpassed through said wide angle reflecting polarizer.
 13. The apparatusof claim 1, wherein the image engine receives the second polarizedportion reflected from said wide angle reflecting polarizer.
 14. Theapparatus of claim 1, wherein the beam of light is directed by the lightsource to the wide angle reflecting polarizer at an angle substantially45° from a surface formed by the reflecting polarizer.
 15. The apparatusof claim 1, wherein the beam of light is directed by the light source tothe wide angle reflecting polarizer at an angle other than substantially45° from a surface formed by the reflecting polarizer.
 16. A method ofproducing a visual image comprising: (a) providing a light sourceproviding a beam of light; (b) directing the light onto a wide anglereflecting polarizer for passing substantially all of a first portion ofthe beam which is polarized in a first direction and for reflectingsubstantially all of a second portion of the beam which is polarized ina second direction; (c) receiving one of the first or second portions inan image engine; (d) shifting the polarity of the one of the first orsecond portions corresponding to an image to be displayed to includecomponents of the second or first portion to yield a polarized image;and (e) returning the polarized image to the wide angle reflectingpolarizer.
 17. The method of claim 16, wherein the wide angle reflectingpolarizer comprises 3M DBEF.
 18. The method of claim 16, furthercomprising reflecting back to the light source which is not part of theimage to be displayed.
 19. The method of claim 16, wherein the lightsource comprises a lamp and a reflecting polarizing filter for passingsubstantially all of the rays of polarized light which are polarized inthe second direction and for reflecting substantially all of the otherrays of light back into the lamp for energy recovery.
 20. The method ofclaim 16, wherein the light source comprises a lamp and a reflectingfilter for passing substantially all rays of selected wavelength bandsand for reflecting substantially all rays of light which are not inthese bands back into the lamp for energy recovery.
 21. The method ofclaim 16, wherein the image engine includes a spatial light modulator.22. The method of claim 16, further comprising modifying the directionof the rays of light.
 23. The method of claim 16, wherein the source ofrays of polarized light comprises: i) an electrodeless lamp body thatdefines a chamber; ii) a gas contained within the chamber; iii)electrodes positioned-eternally of the lamp chamber for producing energythat excites the gas, forming a plasma light source of intense heat thatemits a light beam; iv) wherein the electrodes are not subjected to theintense heat generated at the plasma; v) a reflector positioned next tothe lamp body for redirecting some of the light emitted by the lightsource back to the lamp using the reflector so that the lamp reabsorbslight energy to intensify the light source; and vi) wherein thereflector includes a polarizing filter that is positioned to receive andpolarize the light beam.
 24. The method of claim 16, further comprisingproviding a projection apparatus for producing an image display on adisplay surface, the projection apparatus comprising: i) a displaysurface; ii) an optical device; and iii) means for transmitting lightfrom the lens to the display surface such that the light travels animage path which reaches the optical device twice on its way to thedisplay surface, wherein the optical device is reflective of some lightand transmissive of other light.
 25. A projection display apparatuscomprising: (a) a source of rays of polarized light; (b) a wide anglereflecting polarizer aligned at an angle to the rays of polarized lightfor passing substantially all of the rays of polarized light which arepolarized in a first direction and for reflecting substantially all ofthe rays of polarized light which are polarized in a second direction;(c) a beam splitter/combiner, having a first, primary incidence planealigned at an angle to the wide angle reflecting polarizer, forsplitting incident rays of polarized light from the reflecting polarizerinto a first, second, and third color of light rays; (d) a firstreflecting polarizing LCD for receiving the first color of light raysfrom the beam splitter/combiner, shifting the polarization of none,some, or all of the first color of light rays, and directing the firstcolor of light rays back into the beam splitter/combiner; (e) a secondreflecting polarizing LCD for receiving the second color of light raysfrom the beam splitter/combiner, shifting the polarization of none,some, or all of the second color of light rays, and directing the secondcolor of light rays back into the beam splitter/combiner; (f) a thirdreflecting polarizing LCD for receiving the third color of light raysfrom the beam splitter/combiner, shifting the polarization of none,some, or all of the third color of light rays, and directing the thirdcolor of light rays back into the beam splitter/combiner; and (g) a lensfor receiving and transmitting substantially all of the rays ofpolarized light whose polarity has been shifted and which have passedfrom the beam splitter/combiner to the wide angle reflecting polarizer.26. The apparatus of claim 25, wherein the wide angle reflectingpolarizer comprises 3M DBEF.
 27. The apparatus of claim 25, wherein thefirst, second, and third color of light rays are respectively red,green, and blue light rays.
 28. A projection display apparatuscomprising: (a) a source of rays of polarized light; (b) a wide anglereflecting polarizer aligned at an angle to the rays of polarized lightfor passing substantially all of the rays of polarized light which arepolarized in a first direction and for reflecting substantially all ofthe rays of polarized light which are polarized in a second direction;(c) a beam splitter/combiner, having a first, primary incidence planealigned at an angle to the wide angle reflecting polarizer, forsplitting incident rays of polarized light from the reflecting polarizerinto a first and second color bands of rays; (d) a color wheel/shutterfor receiving the first color band of rays from the beamsplitter/combiner and for sequentially passing rays of a first color andof a second color in the first color band; (e) a first reflectingpolarizing LCD for receiving the sequentially passed rays of the firstcolor and of the second color in the first color band, for shifting thepolarization of none, some, or all of the sequentially passed rays, andfor directing the rays back into the beam splitter/combiner; (f) asecond reflecting polarizing LCD for receiving the second color band forrays from the beam splitter/combiner, for shifting the polarization ofnone, some, or all of the second color band of rays, and for directingthe rays back into the beam splitter/combiner; and (g) a lens forreceiving and transmitting substantially all of the rays of polarizedlight whose polarity has been shifted and which have passed from thebeam splitter/combiner to the wide angle reflecting polarizer.
 29. Theapparatus of claim 28, wherein the wide angle reflecting polarizercomprises 3M DBEF.
 30. The apparatus of claim 28, wherein the firstcolor band is green and blue and wherein the second color band is red.31. A projection system comprising: (a) a source of rays of polarizedlight; (b) a wide angle reflecting polarizer aligned at an angle to therays of polarized light for passing substantially all of the rays ofpolarized light which are polarized in a first direction and forreflecting substantially all of the rays of polarized light which arepolarized in a second direction; (c) a beam splitter/combiner, having afirst, primary incidence plane aligned at an angle to the wide anglereflecting polarizer, for splitting incident rays of polarized lightfrom the reflecting polarizer into a first, second, and third color oflight rays; (d) a first reflecting polarizing LCD for receiving thefirst color of light rays from the beam splitter/combiner, shifting thepolarization of none, some, or all of the first color of light rays, anddirecting the first color of light rays back into the beamsplitter/combiner; (e) a second reflecting polarizing, LCD for receivingthe second color of light rays from the beam spitter/combiner, shiftingthe polarization of none, some, or all of the second color of lightrays, and directing the second color of light rays back into the beamsplitter/combiner; (f) a third reflecting polarizing LCD for receivingthe third color of light rays from the beam splitter/combiner, shiftingthe polarization of none, some, or all of the third color of light rays,and directing the third color of light rays back into the beamsplitter/combiner; (g) a lens for receiving and transmittingsubstantially all of the rays of polarized light whose polarity has beenshifted and which have passed from the beam splitter/combiner to thewide angle reflecting polarizer; and (h) a display surface for receivingrays from the lens.
 32. The apparatus of claim 31, further comprising:an optical device interposed between the lens and the display surfacesuch that the rays travel an image path which reaches the optics twicebefore reaching the display surface, wherein the optical device isreflective of some light and transmissive of other light.
 33. Theapparatus of claim 31, wherein the wide angle reflecting polarizercomprises 3M DBEF.
 34. The apparatus of claim 31, wherein the first,second, and third color of light rays are respectively red, green, andblue light rays.
 35. A projection display apparatus comprising: (a) asource of rays of polarized light; (b) a wide angle reflecting polarizeraligned at an angle to the rays of polarized light for passingsubstantially all of the rays of polarized light which are polarized ina first direction and for reflecting substantially all of the rays ofpolarized light which are polarized in a second direction; (c) a beamsplitter/combiner, having a first, primary incidence plane aligned at anangle to the wide angle reflecting polarizer, for splitting incidentrays of polarized light from the reflecting polarizer into a first andsecond color bands of rays; (d) a color wheel/shutter for receiving thefirst color band of rays from the beam splitter/combiner and forsequentially passing rays of a first color and of a second color in thefirst color band; (e) a first reflecting polarizing LCD for receivingthe sequentially passed rays of the first color and of the second colorin the first color band, for shifting the polarization of none, some, orall of the sequentially passed rays, and for directing the rays backinto the beam splitter/combiner; (f) a second reflecting polarizing LCDfor receiving the second color band for rays from the beamsplitter/combiner, for shifting the polarization of none, some, or allof the second color band of rays, and for directing the rays back intothe beam splitter/combiner; (g) a lens for receiving and transmittingsubstantially all of the rays of polarized light whose polarity has beenshifted and which have passed from the beam splitter/combiner to thewide angle reflecting polarizer; and (h) a display surface for receivingrays from the lens.
 36. The apparatus of claim 35, further comprising:an optical device interposed between the lens and the display surfacesuch that the rays travel an image path which reaches the optics twicebefore reaching the display surface, wherein the optical device isreflective of some light and transmissive of other light.
 37. Theapparatus of claim 35, wherein the wide angle reflecting polarizercomprises 3M DBEF.
 38. The apparatus of claim 35, wherein the firstcolor band is green and blue and wherein the second color band is red.39. A projection display engine apparatus that receives a beam of fightfrom a light source, comprising: a wide angle reflecting polarizer forpassing substantially all of a first polarized portion of the beam thatis polarized in a first direction, and reflecting substantially all of asecond polarized portion of the beam that is polarized in a seconddirection; and an image engine that receives one of the first or secondpolarized portions and returns to said wide angle reflecting polarizer apolarized image in which the polarization of the one of the first orsecond polarized portions is shifted corresponding to an image todisplay to include components of the second or first polarized portion.40. The apparatus of claim 39, wherein the wide angle reflectingpolarizer comprises 3M DBEF.
 41. The apparatus of claim 39, wherein theimage engine further includes a beam splitter/combiner for splittingrays of polarized light received from the reflecting polarizer intoplural color bands, wherein there is a reflecting polarizing LCD foreach color band and an individual planar surface of the beamsplitter/combiner for each color band, and each color band is directedsubstantially through its respective individual planar surface of thesplitter/combiner to its respective reflecting polarizing LCD, andthence through its respective planar surface into the beamsplitter/combiner, where the plural color bands are combined andtransmitted to the wide angle reflecting polarizer.
 42. The apparatus ofclaim 41, wherein the LCD is an analog LCD.
 43. The apparatus of claim39, wherein the image engine further includes a beam splitter/combinerfor splitting rays of polarized light received from the reflectingpolarizer into a first and second color band, wherein the first colorband is passed through a color wheel/shutter to a single LCD for colorsequential operation, and wherein the second color band is passed to asecond LCD.
 44. The apparatus of claim 39 for use with a the lightsource capable of reabsorbing and reemiting light, the apparatus furthercomprising a mirror for reflecting back to the light source light whichis not transmitted to the image engine for reabsorbtion and reemission.45. The apparatus of claim 39, further comprising a means of modifyingthe direction of the rays of light.
 46. The apparatus of claim 39,further comprising: a projection apparatus for producing an imagedisplay on a display surface, the projection apparatus including: i) adisplay surface; ii) an optical device; and iii) means for transmittinglight from the lens to the display surface such that the light travelsan image path which reaches the optical device twice on its way to thedisplay surface, wherein the optical device is reflective of some lightand transmissive of other light.
 47. The apparatus of claim 39, whereinthe image engine receives the first polarized portion passed throughsaid wide angle reflecting polarizer.
 48. The apparatus of claim 39,wherein the image engine receives the second polarized portion reflectedfrom said wide angle reflecting polarizer.
 49. The apparatus of claim39, wherein the beam of light is directed from the light source to thewide angle reflecting polarizer at an angle substantially 45° from asurface formed by the reflecting polarizer.
 50. The apparatus of claim39, wherein the beam of fight is directed from the light source to thewide angle reflecting polarizer at an angle other than substantially 45°from a surface formed by the reflecting polarizer.